title: Antibiotic Resistance in Salmonella enterica Serovar Typhimurium Associates with CRISPR Sequence Type.
abstract: Salmonella entericasubsp.entericaserovar Typhimurium is a leading cause of food-borne salmonellosis in the United States. The number of antibiotic-resistant isolates identified in humans is steadily increasing, suggesting that the spread of antibiotic-resistant strains is a major threat to public health.STyphimurium is commonly identified in a wide range of animal hosts, food sources, and environments, but little is known about the factors mediating the spread of antibiotic resistance in this ecologically complex serovar. Previously, we developed a subtyping method, CRISPR-multi-virulence-locus sequence typing (MVLST), which discriminates among strains of several commonS. entericaserovars. Here, CRISPR-MVLST identified 22 sequence types within a collection of 76STyphimurium isolates from a variety of animal sources throughout central Pennsylvania. Six of the sequence types were identified in more than one isolate, and we observed statistically significant differences in resistance among these sequence types to 7 antibiotics commonly used in veterinary and human medicine, such as ceftiofur and ampicillin (P< 0.05). Importantly, five of these sequence types were subsequently identified in human clinical isolates, and a subset of these isolates had identical antibiotic resistance patterns, suggesting that these subpopulations are being transmitted through the food system. Therefore, CRISPR-MVLST is a promising subtyping method for monitoring the farm-to-fork spread of antibiotic resistance inSTyphimurium.
authors.affiliation: Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: DiMarzio
authors.affiliation: Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA.
authors.forename: Nikki
authors.initials: N
authors.lastname: Shariat
authors.affiliation: Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA.
authors.forename: Subhashinie
authors.initials: S
authors.lastname: Kariyawasam
authors.affiliation: Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA.|Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina, USA.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Barrangou
authors.affiliation: Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA egd100@psu.edu.
authors.forename: Edward G
authors.initials: EG
authors.lastname: Dudley